Drill-hole shooting-plug



E. W. GREINER.

DRILL HOLE SHOOTING PLUG.

APPLICATION FILED 27, I920.

1,385,943. Patented July 26, 1921.

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ERNST W. GREINER, or NEW CASTLE, PENNSYLVANIA.

DRILL-HOLE SHOQTING-IPLUG.

I Specification of Letters Patent.

Application filed February 27, 1920.

of Pennsylvania, have invented certain new and useful Improvements in Drill-Hole Shooting-Plugs; and I do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to an improved drill hole shooting plug. In blasting rocks and the like, it is customary-to drill a hole into the rock into which the blasting charge or explosive is placed. Experiments by persons skilled in this art have disclosed the fact that if the hole is closed when the explosion occurs, a more powerful'rending of the rock will be had, due to the fact that the entire charge will be fired and the gases will be prevented from escaping from the hole, thereby increasing the shattering power of the charge. Sand, clay, and other debris has been employed to some extent to; close the hole, but this method is .poor because such materials are easily blown out of the hole when the explos'ion occurs, and the shattering power'of the charge is not materially increased. This method also includes numerous other disadvantages which are well known to persons skilled in the art, and for this reason will not bemention'ed here.

' There is also another method of increasing the rending power of the explosive. In a great many instances, this method consists of the employment of a tapered body of suit-f able material which co -acts with expanders or the like which surround it. These expanders are generally in-the form of tapered sleeves or segments which are moved into binding engagement with the walls of the drill hole by means of the tapered bod which moves through them when the charge is fired. V I

Devices constructed in the above set forth manner are" almost altogether impractical, and possess many disadvantages. I So far as I am aware, all of these devices include several parts,and when being assembled in the hole, they become disarrange'd because of contact with the rough walls of the drill hole.

When so 'disarranged-they do not operate at 7 all. Another bad feature is that these de Patented July 26, 1921.

Serial No. 361,692.

vices are not effective because of the time consumed by them in frictionally engaging the walls of the hole. To be effective, they must bind against the walls the very instant the charge is fired or else the desired result is unaccomplished. Such devices too, are easily blown out of the hole, and as a whole are not efiective in use. It istherefore one object of this invention to overcome the above circumstances by the employment of an extremely simple device consisting of a single part which is highly effective in use, one which can be easily and readily placed in oper'ative position without becoming disarranged, the construction being such that it is a great deal less expensive than any similar device known to me. In addition to the foregoing, I wish to point out that it is another and very important obj ect of this invention to provide a plug which has its exterior surface gradually tapered from a pointintermediate its center and lower end to form a truncated conical upper portion and a cylindri- I I cal lower portion, the upper end of said truncated portion being circular, flat, andof considerable diameter so as to permit suitable instrument, such as sticks and the like, to be. engaged with it for forcing the plug by ir-' regularities in the wall of the drill hole and effectively and properly seating it on the char e of powder. This is avery important ob ect and feature of the invention and so 1 far as I am aware, prior patented devices are such inconstruction that they do not permit this result to be" accomplished.

Other objects and advantages of the invention will become apparent during the course ofthe following description.

In the accompanying drawings 'formin a partof this specification, and in which like numerals are employed to designate like parts throughout the same:

Figure 1 is a vertical section of a drill hole or blasting chamber, illustrating the manner in which my improved plug is positioned therein. I I I I Fig. 2 is aperspective view of a device con; structed inaccordance with my invention. 7 Referring to the drawings, it will be seen that the numeral 1 indicates a body of rock which has been drilled to provide the drill hole or blasting chamber 2. Assuming'that it is desired to blast the rock surrounding this hole, it will beseen that the bottom of '1 9 W ll l fl With Suitable explosive material 3 which is ignited by means of a detonator f from which the fuse 5 extends.

My invention resides in the peculiarconstruction of the plug which serves to in- V crease the shattering power of explosive material 3. I have designated this plug as a whole, by the numeral 6, the same being made from wood, papier-mach or other suitable material turned or molded to the form shown. The diameter of the cylindrical portion 7 of the plug will be substantially equal to or a little less than the diameter of the drill hole into which it isinserted; This will permit the plug to be slipped into the hole very readily and easily. The length of the plug is immaterial, but I desire it to include the cylindrical portion 7, and the gradually tapered truncated conical portion 8, which is approximately of the total length. of the plug. Such a constructionwill cause the cylindrical portion of the plug to be in close proximity of the walls of the hole 2while the surface of the portion 8will be slightly spaced from these walls. The space formed is tapered and is designed to receive a quantity of spawls 9 therein. Persons skilled in this art are familiar with the word spawls, but in order to enable the reader to obtain a thorough understanding of the word, I will state that they consist of stone or other gritty materials. Extending longitudinally of the plug is a bore 10 through which the fuse 5 passes, and by means of which the plug is guided into the hole. At this point, I wish to again direct attention to the fact that the plug as shown includes a relatively large circular fiat upper end, and this is an important feature since-itpermits suitable instruments to be engaged with this flat end at various points to permit the plug to be forced by any irregularities in the wall of the drill hole and cflectively and easily seated on the explosive charge.

In use, the explosive material 3 is first placed into the hole 2 in the usual manner and the fuse permitted to extend out of the open endof the hole in the manner shown. The fuse is then passed through the hole 10 in the plug, and the latter is run down into the holeby any suitable means,.until it is properly positioned with respect to the ex.

plosivc material 3. Next, a few spawls, con-" si sting of stones or the like are scraped down" into. the hole to fill the space between the tapered portion 8 of the plugand the wall of;

V the hole 2. When inthis position the'plug is ready to resist'the escape of any of the ex plosive gases and by so doing will increase the shattering power of the explosive. By

the employment of the spawls 9, a gritty wedge is formed around the conical portion 8 of the plug, and it is momentarily prevented from being blown out of the drill hole when'the charge is fired. Momentary choking of the drill hole compels full explosion of chips of the gas pressure to be exerted on the rock, thereby increasing the shattering power of the explosive. By shaping the plug in the manner shown ,.and by employing gritty material to wedge it in place, there will be little or no possibility of the plug being blown out ofthe hole.

As before stated, the conception of a drill hole plug employing mechanical principles of friction and expansion in the membersof the-plugs is of course not new. The most practised method of closingthe hole is, as before set forth, by means of clayand other debris, and this practice is satisfactory in a great many instances when the holes are must necessarily possess, that is, it must plug thehole in such a manner as to confine the gas generatedlat the very instant explosion: occurs, and second, it must keep the hole plugged until the rock is; broken. While the method referred to can be made to work under low'pressure conditions, experiments have disclosed the fact thatit does not prove entirely satisfactory when employed with high pressure gases produced by the explosion of dynamite; A, device constructed inv accordance with my inven-v tion will be found greatly superior to many similar devices now in use,ebecause-it consists of a single solid piece. Itrequires no assembling. There are no parts to become disarranged while it is being placed in position on'the'top of the charge through a hole whose walls are not smooth. Furthermore, it can be forced by any irregularities if it should get hung. This may be accomplished .in the manner already set forth. Friction between the plug and the wall is operative the very instant the pressure acts on the base of the plug as the'wedging particles (spawls) are always in wedging position. With an explosion lasting less than, say, 1/1000 of a second, instantaneous friction between the plug and the Wall is ex.- tremely important. The delay of a part of that fraction ofa second is very liable to permit the escape of gas between the plug and the wall of the drill hole. Hence, the failure of'the friction to work the very in-. stant the charge is ignited, permits equal pressure to lift the whole system out of the hole. Friction between my plug and the wall is continuous because of the shape and the employment of the gritty particles in the space between the tapered portion of the plug and the walls of the hole. Singleness and solidness of the plug avoid breakage.

A device constructed in accordance with my invention also possesses advantages over similar devices known to me because of the fact that such a device depends directly on the principle of friction, and not on friction indirectly produced by the principle of expansion. The device is so designed, and is of such dimensions and shape that the gritty material used in connection with it wedges it tightly in position in the drill hole, as soon as this gritty material is introduced. Because of this combination, the friction acts instantaneously and simultaneously with an explosion from the very beginning of the same. Tests made with blocks of leadand stone in quarry practice have proven that the slight fraction of a second gained in the application of the friction between the plug and the wall of the drill hole turns a failure into a success.

From the foregoing description, taken in connection with the accompanying drawings, it is believed that a thorough understanding of the operation and advantages that my device possesses over similar devices is entirely obvious, therefore, further description is deemed unnecessary.

I claim:

A drill hole shooting plug comprisin a relatively long solid substantially cylin ical body provided with a central bore for passage of'a fuse, the exterior surface of said body being gradually tapered from a point intermediate its center and lower end to its upper end, forming a truncated conical upper portion and a cylindrical lower portion, the upper end of said truncated portion being circular, flat, and of consid-.

erable diameter to permit a suitable instrument to be engaged with it for forcing the plug by irregularities in the wall of the drill hole.

In testimony whereof I have hereunto set my hand.

ERNST W. GREINER. 

